Move versions/filelocker into dedicated subpackages, and consistent headers in http requests (#888)

- move filelocker logic into dedicated subpackage
- consistent useragent in requests

Reviewed-on: https://gitea.com/gitea/tea/pulls/888
Co-authored-by: techknowlogick <techknowlogick@gitea.com>
Co-committed-by: techknowlogick <techknowlogick@gitea.com>

modules/filelock/filelock_test.go

@@ -0,0 +1,92 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package filelock
+
+import (
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+	"time"
+)
+
+func TestLocker_WithLock(t *testing.T) {
+	tmpDir := t.TempDir()
+	lockPath := filepath.Join(tmpDir, "test.lock")
+
+	locker := New(lockPath, DefaultTimeout)
+
+	counter := 0
+	err := locker.WithLock(func() error {
+		counter++
+		return nil
+	})
+	if err != nil {
+		t.Fatalf("WithLock failed: %v", err)
+	}
+	if counter != 1 {
+		t.Errorf("Expected counter to be 1, got %d", counter)
+	}
+
+	// Lock file should have been created
+	if _, err := os.Stat(lockPath); os.IsNotExist(err) {
+		t.Error("Lock file should have been created")
+	}
+}
+
+func TestLocker_Acquire(t *testing.T) {
+	tmpDir := t.TempDir()
+	lockPath := filepath.Join(tmpDir, "test.lock")
+
+	locker := New(lockPath, DefaultTimeout)
+
+	unlock, err := locker.Acquire()
+	if err != nil {
+		t.Fatalf("Acquire failed: %v", err)
+	}
+
+	// Lock should be held
+	if unlock == nil {
+		t.Fatal("unlock function should not be nil")
+	}
+
+	// Release the lock
+	if err := unlock(); err != nil {
+		t.Fatalf("unlock failed: %v", err)
+	}
+}
+
+func TestLocker_ConcurrentAccess(t *testing.T) {
+	tmpDir := t.TempDir()
+	lockPath := filepath.Join(tmpDir, "test.lock")
+
+	locker := New(lockPath, 5*time.Second)
+
+	var wg sync.WaitGroup
+	counter := 0
+	numGoroutines := 10
+
+	for i := 0; i < numGoroutines; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			err := locker.WithLock(func() error {
+				// Read-modify-write to check for race conditions
+				tmp := counter
+				time.Sleep(1 * time.Millisecond)
+				counter = tmp + 1
+				return nil
+			})
+			if err != nil {
+				t.Errorf("WithLock failed: %v", err)
+			}
+		}()
+	}
+
+	wg.Wait()
+
+	if counter != numGoroutines {
+		t.Errorf("Expected counter to be %d, got %d (possible race condition)", numGoroutines, counter)
+	}
+}